PNPLA2 and obesity due to melanocortin 4 receptor deficiency: In as much as Atgl deletion only in beta cells is able to protect against obesity-associated complications, this study brings out a new and previously unrecognised role for beta cell ATGL and associated lipolysis-derived GSIS-promoting signal(s) in the control of whole-body energy, insulin and glucose homeostasis, and the development of obesity.